The Clinical Research Core is a fundamental and essential core of our NIH-NIDA funded Center. The goals of the core are: 1) To provide highly trained staff (physicians, nurse practitioners, nurses, and assistants for research) at all levels to perform the rigorous inpatient molecular neurobiology studies as detailed in Project 4, as well as an outpatient site for performance of related genetic studies, as well as for subject screening, evaluation, and follow-up. 2) The second goal is to develop or maintain strong on-site relationships with a limited number of large, successful programs delivering primarily pharmacotherapy for heroin addiction using methadone maintenance or buprenorphine maintenance for: a. Recruitment of subjects for studies at The Rockefeller University Hospital b. In some cases, conducting onsite human molecular genetics ascertainment studies with local clinic IRBs' Informed Consent, as well as Rockefeller University IRB Informed Consent, both signed c. To identify new problems, including psychiatric and medical problems, new drug abuse problems confronting these groups, as well as any unexpected positive or adverse responses to specific treatments. A broad spectrum of subjects in the greater New York area are used for recruitment. Our related clinic in Las Vegas, NV, is used primarily for identification of problems and confirming or refuting the generalizability of observations made in the greater New York area in another part of our nation. 3) The third goal is to provide a nurturing and rigorous environment for the training of clinical investigators, including physicians, nurse practitioners, research nurses, counselors, psychologists, and a wide variety of healthcare personnel, including social workers and counselors interested in becoming directly involved in addictive diseases research or for the purpose of general education and training in research medicine and/or addictive diseases treatment.